Healthy Development Measurement Toolkit

Indicator ST.2.f Proportion of average income spent on transportation expenses

Data Source

Applied Geographic Solutions, Inc. Spring 2007 Update: Current Year Estimates. Methodology available at: http://www.appliedgeographic.com/library.html.

Map data is presented at the level of the census tract, which was calculated by assigning census block data to census tracts based on spatial location. The map also includes planning neighborhood names, in the vicinity of their corresponding census tracts.

Table data is presented by planning neighborhood. While planning neighborhoods are larger geographic areas than census tracts, census tracts do not always lie completely within a planning neighborhood. SFDPH used ArcGIS software and a 'centroids within' methodology to convert census blocks to geographic mean center points. We then assigned census blocks to planning neighborhoods based on the spatial location of those geographic mean center points and calculated the planning neighborhood totals for the table.

Detailed information regarding census data, geographic units of analysis, their definitions, and their boundaries can be found in the HDMT at the following links:

http://www.thehdmt.org/etc/Geographic_Units_of_Analysis.September_2009.pdf

http://www.thehdmt.org/data_map_methods.php

Explanation and Limitations

In the table above, the percentages represent the proportion of total household expenditures spent on transportation expenses. This data was obtained from the Applied Geographic Solutions, Inc. 2007 data for San Francisco, which derived the data from an extensive modeling effort based on household demographic data using the 2005 Consumer Expenditure Survey data from the Bureau of Labor Statistics comprehensive nationwide survey.

Transportation expenditures could include those that are vehicle-related (purchases, vehicle finance charges, gasoline and motor oil, maintenance and repairs, vehicle insurance, vehicle rentals, leases, licenses and other charges) or those that are public transit-related (fares for mass transit, buses, trains, airlines, taxis, boats).

Total expenditures consist of the transaction costs, including excise and sales taxes, of goods and services. Expenditure estimates include expenditures for gifts, but exclude purchases or portions of purchases directly assignable to business purposes. Also excluded are periodic credit or installment payments on goods or services already acquired. The full cost of each purchase is recorded, even though full payment may not have been made at the date of purchase. Expenditures given in this survey occur at the level of the household.

More detail regarding the Bureau of Labor Statistics' Consumer Expenditure survey is available at http://www.bls.gov/cex/home.htm

Proportion of total expenditures spent on transportation is impacted by factors including income level, distance traveled to work, and availability of public transit. While the information above does not stratify expenditure by income levels, research illustrates that low and high income households spend comparable percentages of their budget on transportation costs, despite higher rates of vehicle ownership among wealthier households. According to a report by the Public Policy Institute of California (PPIC), transportation was the third-largest budget item for low-income households in California's metropolitan areas; spending on housing and food ranked first and second. For higher-income households, transportation replaced food as the second-largest budget item (again, partially explained by higher rates of vehicle ownership). In urban areas, low-income households allocated a slightly smaller proportion of their household expenditures to transportation than did higher-income households.^a

Why is this a Community Health Indicator?

As transportation expenditures continue to rise, the amount households have to spend on housing, food, health care, insurance, education, and other needs decreases. Prohibitive transportation costs can interfere with employment prospects, economic self-sufficiency, and access to needed goods and services including health care and food. Providing affordable public transportation, particularly to transit dependent and low income communities, is one way to address these inequities in access that negatively impact on health.